... continuously variable optical signal attenuation. FG590 handhold optical variable attenuator is used for continuously variable optical signal attenuation. ... testing, there, therefore FG590 can be used in the digital system of communication devices (such as: PHD, SDH) ... (CATV).♦ Features• Stepwise attenuating by circumgyrated dial: attenuating step 0.05dB, 2.5~60dB continuously adjustable.• Provide with ...